A week-long preliminary hearing, essentially a dress rehearsal for trial, has included graphic details never before revealed to the public. During Tuesday's preliminary hearing, two 911 calls were played for the courtroom.

911 CALLS

The first 911 call was only 20 seconds long. The call came from a Kevin Quinonez who was inside theater 9. During those 20 seconds, you can hear at least 30 gunshots going off in the background.

Detective Randy Hansen recalled both phone calls for the court.

The second 911 call was a 4-minute long call made by a 13-year-old girl. She is the cousin of Ashley Moser and Veronica Moser-Sullivan. Veronica is a 6-year-old who passed away during the shooting. Ashley is her mother. During this 911 call, the caller sounded desperate. The following is a transcription of what the caller told the dispatcher:

Dispatcher: Who's been shot
Answer: My two cousins. [They are] on the floor. [They are] not breathing.
Dispatcher: I'm going to walk you through the steps. You need to start CPR
Answer: I can't
Dispatcher: We need to start CPR on your cousin
Answer: My cousin's been shot. The police are here.

The caller was frantic, saying multiple times that she could not hear the dispatcher. A few times, the caller shouted "Help me."

During the 911 call, Veronica's father, Ian Sullivan, had his eyes closed and was crying.

INSIDE HOLMES' CAR AND APARTMENT

FBI Special Agent Garrett Gumbinner is a bomb technician with the FBI. When he took the stand, Gumbinner described clearing Holmes' car at the scene.

Holmes had put a sunshade on his windshield, according to Gumbinner, making it difficult to see inside. There were no explosives in the car, but police did find a handgun on the roof, another handgun in the passenger door compartment, a ballistic neck protector, backpack rifle containers, an iPhone shoved between the passenger and driver's seats and vehicle deterrent spikes (otherwise known as spike sticks) on the passenger seat.

When investigating Holmes' apartment, police found a trip wire that connected from the door jamb to a Thermos. The Thermos was at a 45-degree angle and full of glycerin. Police say it was set to spill into a frying pan which was full of potassium permanganate. The intent of that was to create a chemical reaction that would create sparks when the trip wire was tripped.

Gumbinner showed the court photos of inside Holmes' apartment. There were at least five jars which Holmes had described as "improvised napalm devices." According to the testimony, Holmes used household items like aluminum rods to make the explosive devices. Some of the explosives, when burning, would be too hot to put out of water. Some of the jars were full of chemicals, and others were full of bullets. There were six-inch firework shells with three-inch shells inside filled with smokeless powder and gas oil. If the carpet had caught fire, the apartment could have exploded.

"Some of the reactions of these different chemicals would create a very hot fire. Some of them would create a lot of smoke," former FBI agent Rick Hahn told 9NEWS via Skype from his home in California."Clearly he wanted to create a lot of chaos. He wanted to hurt a lot of people."

According to Gumbinner, Holmes had three initiating systems in his apartment: a trip wire, a pyrotechnic firing box and a launch-control system. The firing box was controlled by a remote control which was placed outside the apartment in a garbage bag.

Inside that trash bag, Holmes had also placed a boom box and a remote-controlled car. On the boom box was a CD playing which had 49 minutes of silence and then loud music cued to play. Holmes reportedly told police his hope was the music would start, someone passing by would go toward the music, become interested in the remote-controlled car and start playing with the car. At that point, since the remote control was connected to the firing box in the apartment, it would trigger an explosion in the apartment. Another witness later testified the car and remote were never recovered.

"This guy clearly put in a lot of work and a lot of research into this. He had a plan B, plan C sort of thing," Hahn said. "There were backups to make sure to get fire, smoke and explosions."

HOLMES' WEAPONS PURCHASES

ATF Special Agent Steven Beggs testified on Tuesday and outlined the number of guns and ammunition Holmes purchased from May 2012 until July 2012.

Some of the guns and ammo were purchased online, Beggs said, however some of the explosives and other weapons were purchased in person at various locations around the city.

He had four firearms in total: two handguns, a shotgun and a rifle in his apartment. He had more than 6,200 rounds of ammunition.

The defense asked Beggs if there is any legal process to prevent a "severely mentally-ill person" from purchasing the guns and ammo. Beggs said "No."

FILING DETECTIVE TESTIMONY

Detective Craig Appel testified on Tuesday regarding what happened after police took Holmes into custody.

According to Appel, they took arrested Holmes in his boxers, T-shirt and socks. After they took off his handcuffs, they placed paper bags over his hands to preserve gun powder residue. Appel said Holmes started to use his hands like they were talking puppets. At one point, Holmes reportedly ripped a staple out of the table and tried to stick the staple in an electric outlet.

The defense asked Appel why he did not take a blood sample from Holmes to see if he was under the influence. They cited his pupil size, which was very large. Appel testified he did not see extensive evidence that Holmes was under the influence.

THE SCOPE OF THE INVESTIGATION

Aurora Police Sgt. Fyles testified Tuesday on the scope of the investigation. He said 444 different officers authored reports related to the case and 56 crime technicians analysed evidence. Overall, he testified that 1000 people worked on the case.

During the investigation, police interviewed at least 370 people from both theater 9, where the shooting took place, and an adjacent theater.

PRELIMINARY HEARING DAY 1

Monday marked the first day of the preliminary hearing. A couple of the officers who took the stand on Monday got quite emotional, often holding back tears as they described a chaotic scene with bloody victims and a parking lot so packed that ambulances could not get access.

Appel clarified Holmes purchased his ticket to the showing on July 7, not July 8 as was previously mentioned in Monday's testimony.